Snap hooks have a latch that is movable between an open and a closed position, and when in the closed position, the latch bridges the open end or throat of the hook. When it is desired to connect the snap hook to a support device, the latch is moved to the open position to provide an entry clearance through the open end of the hook for the support device. After the snap hook is installed, the latch is moved back into the closed position to minimize the possibility that the snap hook will be accidentally disconnected from the support device.
Ceiling Mounted Transport Systems ("CMTS's") utilize overhead tracks that are oftentimes positioned at the internal ceiling of a structure such as a nursing home or warehouse. These systems include a roller mounted plate attached to the track that can roll back and forth to desired locations along the length of the track. A support device such as a U-shaped bar depends downward from the rolling plate and is used to support a hoist, which in turn is used to support and lift a load. CMTS's are particularly advantageous for transporting non-ambulatory persons, because the system is capable of lifting the disabled person above obstacles commonly found in environments such as homes, nursing homes, and hospitals. A typical CMTS hoist includes a strap or chain that can extend out of and retract into the body of the hoist, and the upper end of the strap has a snap hook for connecting to the support device depending from the rolling plate. A harness or other support device depends from the lower surface of the hoist and is secured to the load, which is lifted by operating the hoist to retract the upper strap into the body of the hoist. Some CMTS's use portable hoists, i.e., hoists that can be disconnected from one CMTS and relocated for use on a CMTS at a different location. The advantage of using a portable hoist is that it reduces the overall cost of operating multiple CMTS's.
Portability is particularly desirable in CMTS's used for transporting non-ambulatory disabled persons (i.e., "non-ambulatory CMTS's"). Given the frequency with which a hoist is used in a non-ambulatory CMTS as well as the need to curtail the costs associated with medical care, it is not always cost effective to have a dedicated hoist at each CMTS administered by a caregiver tending to the needs of the disabled. Thus, any advances in the art that will enhance the portability of a CMTS hoist is highly desirable, and particularly so when the hoist under consideration is used in non-ambulatory CMTS's.
To remove a portable hoist from the rolling platform in a typical non-ambulatory CMTS, the operator first lowers the hoist onto a platform or the floor to relieve the load placed on the snap hook by the weight of the hoist. Locating and positioning a platform beneath the hoist is inconvenient and lowering the hoist to the floor is undesirable since the operator is exposed to potential back injuries when later lifting the hoist from the floor. Moreover, since hoists used in non-ambulatory CMTS's are usually lightweight enough to be hand carried, this step could be eliminated altogether if a means existed for disconnecting the snap hook from the rolling platform while the operator manually supports the weight of the hoist.
After the weight of the hoist is removed from the snap hook, a person of typical height must use a step ladder, stool, etc., to access the snap hook to move the latch into the open position. The use of a stepladder or stool is undesirable, since the operator may fall when disconnecting the snap hook. The possibility of a fall is aggravated by the fact that, while standing on the step ladder, the operator must devote his or her attention to moving the latch into the open position so that the snap hook can be disconnected from the roller plate.
A CMTS device known in the art that eliminates the need for a step ladder uses a shaft or pole that is permanently attached to a hook that is connected to the roller platform. The shaft depends downward from the hook far enough for an operator who is standing on the floor to grasp the shaft and remove the hook from the roller platform. However, since the shaft is permanently attached to the hook, it moves with the platform from one position on the track to another and may thus interfere with obstacles lying in the same path as the track. Additionally, the hooks attached to the angled shafts do not include a latch--the purpose of using an angled shaft would be defeated if the hook included a latch, since the operator would need a stepladder to access the hook to open the latch.
An example of a snap hook with a detachable shaft is shown in U.S. Pat. No. 3,913,515 to Hernsjo. However, while the shaft in Hernsjo is useful for installing a snap hook onto a support member, the shaft does not include a means for opening the latch. Consequently, the operator must still access the snap hook with his or her hands to open the latch, when disconnecting the snap hook.
Snap hooks with remotely operable latches are known in the art. For example, in U.S. Pat. No. 4,195,872 to Skaalen, the latch is opened by a pulling on a tether line that extends through the body of the hook. A similar snap hook is disclosed in U.S. Pat. No. 5,538,303 to Dunham. However, while these tether lines allow an operator to open the latch from a remote position, they do not provide a safe and controllable means of removing the snap hook from an overhead support device. U.S. Pat. No. 2,246,630 to Johnson discloses a snap hook for connecting to electric power lines having a latch that is opened by a lever operated camming mechanism, and the lever includes an eyelet to which a tether line might be attached. However, this device includes moving parts positioned external to the body of the hook, including above the top of the hook, which could interfere with the mounting of a snap hook to a roller platform in a CMTS. Moreover, hooks with external moving parts are undesirable in many applications because of the possibility of entanglement in clothing, furniture, and medical equipment.
U.S. Pat. Nos. 2,116,880 to Dee and 5,622,399 to Albright disclose snap hooks that use a shaft to remotely operate the latch, and the shaft also serves as a handle for removing the snap hook from a support device. However, the motion of the shaft when opening the latch in these hooks is parallel with the line supporting the load connected to the snap hook. Consequently, if the shaft is used while the snap hook is suspending a hoist, there is a potential for interference between the shaft and the hoist. Moreover, the shaft is detached from the hook by rotating the shaft, and the shaft may be accidentally disconnected if the shaft is inadvertently rotated.
Another patent of general interest is U.S. Pat. No. 5,490,293, which discloses an apparatus used to transfer a hoist from one track in a CMTS to an adjacent track. This apparatus does not address the portability needs encountered when the hoist must be moved from one location (e.g., nursing home) to another location (e.g., private home).
From the foregoing, it is seen that it is highly desirable to have a snap hook, particularly for use in connection with portable hoists used in non-ambulatory CMTS's, with a simpler, more compact, and more streamlined construction than prior art snap hooks. It is also desirable to have a snap hook with a latch that is remotely operable by a shaft while the hoist is suspended from the hook. Such a snap hook will allow an operator to remotely open the latch, and then remove the snap hook from a support device while the operator is simultaneously supporting the weight of the hoist, and will eliminate the inherent danger involved in using a stepladder to access the snap hook to open the latch.